Standby generator with two meters?

[reader2580]

I am helping my brother with electrical design for his new house. One of the things he is going to do is heat pumps with natural gas backup. He will have two meters as the heat pumps will be on a plan that can interrupt service in exchange for a much cheaper rate. It appears that the power company will hook up each meter directly to the grid versus sub metering.

How would a standby generator work in this case if he wants to power the heat pumps in the summer to still have A/C in a power outage? The generator would probably be 20 KW with load shed.

 

[jkeyser14]

FYI, this may not be a money saving approach. You need to check to see how much the power company charges for the second meter. If it's $40 a month extra he may not realize any cost savings.

If you need emergency generator backup on both the emergency heat and the heat pumps, you will also need two generators, as you can't branch both services with a generator.

 

[reader2580]

Monthly charge is $5. Electricity is 4.5 cents versus 10 cents normal. It looks like break even is about 80 KWh per month.

I kinda figured there isn’t a way to use one generator for both. I’m pretty sure he would give up A/C in an outage and get a smaller generator to save money. He will have sewage lift station.

 

[mm08822]

You could use 1 generator but would require 2 automatic xfer switches – each xfer switch is connected after the respective meter. Xfer switches operate in parallel. One is the master, the other is a slave.

 

[Stuart in MN]

You could use 1 generator but would require 2 automatic xfer switches – each xfer switch is connected after the respective meter. Xfer switches operate in parallel. One is the master, the other is a slave.

Assuming we're talking about automatic transfer switches, I agree.

 

[reader2580]

You could use 1 generator but would require 2 automatic xfer switches – each xfer switch is connected after the respective meter. Xfer switches operate in parallel. One is the master, the other is a slave.

Do any of the big standby generator manufacturers have auto transfer switches that work like this? I have never heard of doing master/slave transfer switches before.

My brother is cheap so I wouldn't doubt he just decides to do only a small standby generator, or none at all. My father and I are both suggesting he put in a standby generator especially with the lift pump. The house he is building is huge and the generator would be a rounding error in the big scheme of things. He will have a small indoor pool, sport court, and a four car garage.

 

[wyliesdiesels]

Your brother is cheap yet he is building a mansion with all that stuff?

I dont call that cheap...

 

[mm08822]

Do any of the big standby generator manufacturers have auto transfer switches that work like this? I have never heard of doing master/slave transfer switches before.

My brother is cheap so I wouldn't doubt he just decides to do only a small standby generator, or none at all. My father and I are both suggesting he put in a standby generator especially with the lift pump. The house he is building is huge and the generator would be a rounding error in the big scheme of things. He will have a small indoor pool, sport court, and a four car garage.

Master/slave was not the best terms to use, but good enough.

For a Generac xfer switch system, you would purchase 2 xfer switches of same style each with switched neutrals. (Standard equipment does not come with switched neutrals.)

The first switch gets all control wires connected between it and generator typical of any standard installation:
N1 & N2 – Utility Sense lines
T1 – battery charger
23 – Transfer switch control signal wire (gets sunk to common at gen controller when xfer required)
194 - +12VDC from gen
0 – Vdc common from gen

To connect the 2nd xfer switch:
Only need to connect:
23 – Transfer switch control signal wire (gets sunk to common at gen controller when xfer required)
194 - +12VDC from gen
0 – Vdc common from gen (not needed but easier to have for troubleshooting purposes)
These 3 wires can come from the first xfer switch or directly from the gen.

Generator power output is paralleled to both xfer switches.

 

[jeepxj]

Do any of the big standby generator manufacturers have auto transfer switches that work like this? I have never heard of doing master/slave transfer switches before.

My brother is cheap so I wouldn't doubt he just decides to do only a small standby generator, or none at all. My father and I are both suggesting he put in a standby generator especially with the lift pump. The house he is building is huge and the generator would be a rounding error in the big scheme of things. He will have a small indoor pool, sport court, and a four car garage.

Yup. tons of generators out there can handle 2 transfer switches.

 

[theoldwizard1]

Yup. tons of generators out there can handle 2 transfer switches.

If you are using an automatic starting generator, most building authorities now require a generator that is capable of providing the MAXIMUM power that the building could require OR a way to cut out some loads (typically A/C or water heater).

 

[wyliesdiesels]

If you are using an automatic starting generator, most building authorities now require a generator that is capable of providing the MAXIMUM power that the building could require OR a way to cut out some loads (typically A/C or water heater).

aka load shedding

 

[reader2580]

If you are using an automatic starting generator, most building authorities now require a generator that is capable of providing the MAXIMUM power that the building could require OR a way to cut out some loads (typically A/C or water heater).

I believe that is actually an NEC requirement. Transfer switches often include load shed capabilities.

I did a sub panel because I couldn’t easily reroute my feed from the meter through a transfer switch to power everything.

 

[reader2580]

Your brother is cheap yet he is building a mansion with all that stuff?

I dont call that cheap...

Maybe I should have said extremely frugal instead. He buys a lot of used stuff and sometimes spends a lot of money fixing the stuff. He will spend hours trying to find a deal when he does buy new. He buys a lot from EBay.

He is acting as the general contractor for his house to save money, plus doing some of the work.

 

[Showkey]

On separate issue.........in my area people with ground to air heat pumps are not using them and run the NG backup. NG prices have dropped since the installs of these hybrid systems. ...........so NG is more comfortable ( warmer discharge) and cost less to operate.
Obviously this will vary by location, power company incentives, climate, time of use metering etc..........but...........do your research.........be prepared for changes in the power costs.

Many of these heat pump systems were design and built to get away from the high cost of propane........when NG became available it completely changed the economics.

 

[jeepxj]

Maybe I should have said extremely frugal instead. He buys a lot of used stuff and sometimes spends a lot of money fixing the stuff. He will spend hours trying to find a deal when he does buy new. He buys a lot from EBay.

He is acting as the general contractor for his house to save money, plus doing some of the work.

not a chance in hell that works out.

 

[dcg9381]

not a chance in hell that works out.

Around here there are zero requirements to be a "home builder". So I call myself a home builder and I am.... It's kinda wild west.

Ruling him out because he's the GC probably isn't a good call... Many of us are building our own structures as "GC".

 

[jeepxj]

Around here there are zero requirements to be a "home builder". So I call myself a home builder and I am.... It's kinda wild west.

Ruling him out because he's the GC probably isn't a good call... Many of us are building our own structures as "GC".

I'm really referring to the comment from a few posts up about how cheap he is. a no experience GC who is trying to cut corners to save costs will never end up spending less in the long run.